U.S. patent number 4,562,650 [Application Number 06/587,703] was granted by the patent office on 1986-01-07 for board drying apparatus.
This patent grant is currently assigned to Hashimoto Denki Co., Ltd.. Invention is credited to Eiichi Itoh, Sadao Kato, Kiyoshi Nagasawa.
United States Patent |
4,562,650 |
Nagasawa , et al. |
January 7, 1986 |
Board drying apparatus
Abstract
A board drying apparatus includes a pair of fork conveyors
provided in a housing and disposed vertically with spacing
therebetween. Each fork conveyor has a number of extension arms
fixed at to said fork conveyor to extend substantially at right
angles therewith. These extension arms of both of the fork
conveyors are associated with each other in such a manner that each
of the extension arms of one of the fork conveyors is arranged at
the same level as the associated extension arm of the other of the
fork conveyors and that the extension arms on the inner side of
each fork conveyor are opposed to each other and move downwardly at
the same speed. A board to be dried is supplied to the uppermost
horizontal extension arms at the inner sides of the fork conveyors
and is carried downwardly by the extension arms during which the
board is dried by heated air circulated through space between the
fork conveyors in the lengthwise direction of the boards.
Inventors: |
Nagasawa; Kiyoshi (Chita,
JP), Itoh; Eiichi (Tokai, JP), Kato;
Sadao (Tokai, JP) |
Assignee: |
Hashimoto Denki Co., Ltd.
(Aichi, JP)
|
Family
ID: |
12826829 |
Appl.
No.: |
06/587,703 |
Filed: |
March 8, 1984 |
Foreign Application Priority Data
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|
|
|
|
Mar 23, 1983 [JP] |
|
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58-49292 |
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Current U.S.
Class: |
34/612; 271/192;
34/236 |
Current CPC
Class: |
F26B
15/22 (20130101) |
Current International
Class: |
F26B
15/22 (20060101); F26B 15/00 (20060101); F26B
015/20 () |
Field of
Search: |
;34/107,149,219,227,236
;198/607,611,782,424 ;271/192,189 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Schwartz; Larry I.
Assistant Examiner: Westphal; David W.
Attorney, Agent or Firm: Wenderoth, Lind & Ponack
Claims
What is claimed is:
1. A board drying apparatus comprising:
a substantially closed housing;
a pair of fork conveyors disposed vertically in said housing with
spacing therebetween and having inner sides opposed to each
other;
each fork conveyor having a plurality of extension arms fixed at
ends thereof to said fork conveyor to extend substantially at right
angles thereto, in such a manner that each of said extension arms
of one of said fork conveyors has an associated extension arm at
the same level on the other of said fork conveyors, and that the
said extension arms on said inner sides of said fork conveyors are
opposed to each other and are moved downwardly at the same
speed;
means for feeding boards to be dried to the uppermost horizontally
positioned said extension arms at said inner sides of said fork
conveyors, said feeding means comprising a delivery conveyor
provided above and between said pair of fork conveyors, said
delivery conveyor including a pair of swingable arms operable to be
opened at lower portions thereof in the manner of a gate;
means for discharging the dried boards from the lowermost position
of said fork conveyors;
heating means for producing heated air in said housing;
blower means for circulating the heated air through space between
said fork conveyors; and
said blower means and said heating means being disposed in series
in the horizontal direction at a side portion in the interior of
said housing to cause the heated air to flow through said space
between said fork conveyors in the lengthwise direction of the
boards supported thereby.
2. A board drying apparatus as claimed in claim 1, wherein each of
said fork conveyors includes front and rear endless chains arranged
in a double row, said endless chains having connected thereto said
extension arms in the form of frame-like members spaced at
intervals.
3. A board drying apparatus as claimed in claim 1, wherein said
discharge means comprises a discharge conveyor belt provided
directly below and between said pair of fork conveyors, whereby a
dried board dropping downwardly from the lowermost said extension
arms is placed on said discharge conveyor belt.
4. A board drying apparatus as claimed in claim 1, wherein said
heating means comprises upper and lower heaters, and said blower
means comprises upper and lower fans disposed in series with said
upper and lower heaters, respectively, said upper and lower fans
having reverse blowing directions.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a board drying apparatus for
drying boards which still contain a large amount of water such as,
for example, veneer, calcium silicate board, pulp cement board,
plaster board and fiber board.
A conventional board drying apparatus includes a wicket type drying
machine having a fork conveyor. In this fork conveyor, a plurality
of endless chain conveyors each having a number of extension arms
like a comb are arranged side by side in the horizontal direction.
A feed conveyor for a board to be dried and a discharge conveyor
for the dried board are arranged horizontally at opposite ends of
the fork conveyor in such a manner that ends of the feed conveyor
and discharge conveyor partially extend into spaces between the
endless chain conveyors forming the fork conveyor. A relatively
large board to be dried and carried by the feed conveyor is fed in
the horizontal direction to one end of the fork conveyor, from
where the board enters into a space between the adjacent extension
arms and then gradually is erected as the extension arms rise from
the horizontal to the vertical by the rotation of the endless chain
conveyors. Thus, the board to be dried is vertically held by the
adjoining extension arms and carried along a horizontal path of the
endless chain conveyors during which drying treatment is carried
out. The dried board is discharged onto the discharge conveyor from
the other end of the fork conveyor while the board turns from the
vertical to a horizontal posture.
However, in the conventional wicket type drying machine, ends of
the feed conveyor and discharge conveyor partially enter into
spaces between the endless chain conveyors which are arranged side
by side and have many extension arms to form the fork conveyor.
Accordingly, when boards of small size are to be treated by the
convetional wicket type drying machine, there is a possibility that
such small boards fall down through the space between the adjacent
extension arms, whereby delivery of the boards onto and out of the
fork conveyor is troublesome.
Also, in the conventional wicket type drying machine, small boards
having small widths will often fall down in the transverse
direction of the fork conveyor when the boards are erected from the
horizontal posture at the feeding end of the conveyor, especially
when the boards have an irregular shape at the front end thereof.
This will prevent continuous transfer of the boards to be
treated.
Further, according to the ordinary transfer mode in conventional
wicket type board drying machines of this type, boards to be dried
are fed first horizontally, then erected vertically halfway at the
transfer path and moved, and thereafter again returned to the
horizontal posture. Consequently, when a board is erected
vertically during transfer, the moisture contained therein moves
downward due to gravity, thus causing a remarkable bias in moisture
distribution in the vertical direction, which leads to an imbalance
of moisture content in a finished state and an arcuate deformation
due to the difference in shrinkage at front, rear, right and left
portions of the board. Thus, the product quality is badly
deteriorated.
Accordingly, an object of the present invention is to eliminate
these drawbacks of the conventional board drying apparatus.
Another object of the present invention is to provide a board
drying apparatus which causes no difficulty in the delivery of the
boards from a feed conveyor and to a discharge conveyor.
A further object of the present invention is to provide a board
drying apparatus which can smoothly transfer not only a large sized
board but also a small sized board for drying treatment, even
though the board has an irregular shape at the front end
thereof.
Still another object of the present invention is to provide a board
drying apparatus which can homogeneously dry the board without an
imbalance of moisture content.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a board
drying apparatus which comprises a closed housing, a pair of fork
conveyors provided in the housing and disposed vertically with
spacing therebetween, each fork conveyor having a number of
extension arms fixed at ends thereof to the fork conveyor
substantially at right angles therewith in such a manner that each
of the extension arms of one of the fork conveyors has an
associated extension arm at the same level on the other of the fork
conveyors and that the extension arms on the inner side of each
fork conveyor are opposed to each other and move downwardly at the
same speed, means for feeding boards to be dried to the uppermost
horizontally positioned extension arms at the inner sides of the
fork conveyors, means for discharging the dried boards from the
lowermost position of the fork conveyors, heating means for
generating heated air in the housing, and blowers for circulating
the heated air through space between the fork conveyors in the
lengthwise direction of the boards.
Preferably, the board feeding means comprises a feed conveyor
provided above and between the pair of fork conveyors. The feed
conveyor has a pair of swingable arms which can open at the lower
part thereof like a gate, whereby a board on the feed conveyor is
placed horizontally on the uppermost horizontal extension arms of
the form conveyors.
Other objects and features of the present invention will become
apparent from the following detailed explanation of a preferred
embodiment of the present invention, when taken in conjunction with
the accompanying drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view, partially broken away, of a board drying
apparatus according to a preferred embodiment of the present
invention,
FIG. 2 is a side view of the apparatus shown in FIG. 1, and
FIG. 3 is a plan view of the apparatus shown in FIG. 1.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION
A board drying apparatus according to a preferred embodiment of the
present invention comprises a closed housing 9 in which a pair of
fork conveyors 2a and 2b are disposed vertically with spacing
therebetween. Each fork conveyor 2a or 2b has front and rear
endless chains (C) in a double row which are entrained about upper
and lower sprockets (S). The endless chains (C) in the row have a
number of frame-like extension arms (F) at suitable intervals. Each
extension arm (F) is formed by connecting metal rods in a
rectangular configuration and fixed at ends thereof to the chains
in the row at right angles with the latter. These extension arms
(F) of the fork conveyors 2a, 2b are arranged in such a manner that
each of the extension arms of one of the fork conveyors has an
associated extension arm at the same level on the other of the fork
conveyors and that extension arms on the inner side of each fork
conveyor are opposed to each other and move downwardly at the same
speed. The length of the extension arms (F) for supporting opposite
sides of a board to be dried is set at an appropriate value while
taking into account the flexibility and strength of the board. It
should be noted here that the distance between the front and rear
endless chains in each fork conveyor is greater than the distance
between the front endless chains or rear endless chains of the two
fork conveyors 2a and 2b, so that a large rectangular shaped board
longer in the front-to-rear direction can be treated for
drying.
Provided above and between the fork conveyors 2a, 2b is a delivery
conveyor having a pair of gate-like swingable arms 3a and 3b. The
swingable arms 3a and 3b are opposed to each other in the form of a
gate and, when closed, support the board to be dried horizontally
from both sides thereof. When the swingable arms 3a, 3b are opened,
the board is dropped onto the uppermost horizontally positioned
extension arms (F) of the fork conveyors 2a and 2b. Thus, the
delivery conveyor is so constructed as to repeat such intermittent
opening and closing delivery operations.
In line with the delivery conveyor 3a, 3b is a feed conveyor 7
which extends from one end portion of the delivery conveyor to the
outside of the housing 9. The boards to be dried are fed from the
feed conveyor 7 to the delivery conveyor and then to the fork
conveyors 2a, 2b as set forth hereinabove.
Provided below and between the conveyors 2a and 2b is a discharge
conveyor 4 which extends horizontally beyond the housing 9. This
discharge conveyor 4 is arranged to receive the dried board from
the lowermost pair of extension arms (F) when the latter open
downwardly like a gate by rotating about the respective lower
sprockets. The dried board thus received by the discharge conveyor
4 is carried outside of the housing 9 by a transport conveyor
8.
The housing 9 also includes fans 5a, 5b and heaters 6a, 6b disposed
in series at a side portion in the interior thereof. The heaters 6a
and 6b may be in the form of steam-heated Aerofine heaters. As an
example of other heating sources, hot gas may be introduced into
the housing 9 directly from a boiler.
For supplying and circulating hot air between layers of boards 1 to
be dried as the boards continue to move downwardly while being
horizontally supported and carried by the fork conveyors 2a and 2b,
the hot air supply region usually is divided into upper and lower
or upper, middle and lower sections, and the temperature and
humidity of each hot air supply section are made adjustable in
accordance with drying conditions. For example, as shown in the
drawings, the upper and lower two-stage fans 5a, 5b and heaters 6a,
6b or other heating source divide the hot air supply region into
upper and lower sections, and in many cases the upper and lower
blowing directions are reversed to make the degree of drying
uniform.
Further, though not shown, distributors of an appropriate shape are
disposed before and behind the fork conveyors 2a and 2b which serve
as the hot air circulating path in the housing 9. Such distributors
cooperate with buffer chambers disposed just therebefore so that
the distributed hot air portions may act uniformly on the upper,
lower, right and left sides of the boards 1.
Now, referring to the operation of the board drying apparatus of
the present invention shown in FIGS. 1 to 3, a board to be dried is
first fed onto the delivery conveyor 3 by means of the feed
conveyor 7, and the presence of the board is detected by a detector
such as a limit switch disposed in a suitable position. A signal
from such detector activates an actuator such as an air cylinder
for operating the gate-like swingable arms 3a and 3b, whereby the
arms 3a and 3b are opened and the board is placed horizontally onto
the uppermost horizontal pair of extension arms F of the fork
conveyors 2. Thus, the boards are successively put on the extension
arms F and then carried downwardly. During this downward movement
the boards are exposed at both faces thereof to hot air produced
and circulated in the horizontal direction by the heaters 6a, 6b
and fans 5a, 5b and thereby dried rapidly. It should be noted here
that since the heaters 6a, 6b and fans 5a, 5b are disposed in
series at one side portion of the housing 9, the hot air is
circulated through the space between the fork conveyors, as shown
by arrows in FIG. 3. This means that the hot air flows along the
lengthwise direction of the boards 1 to be dried. Such a flow
pattern of the hot air minimizes curling or bending of the dried
boards compared with a flow pattern of hot air in the sidewise
direction of the boards. Especially, when the flow direction of the
hot air caused by the upper fan 5a and upper heater 6a is reversed
with that caused by the lower fan 5b and lower heater 6b, more
homogeneous drying can be achieved with less curling or bending of
the board. Then, the boards 1 thus dried are discharged
successively from the lowermost extension arms F of the fork
conveyor onto the just underlying discharge conveyor 4 and carried
out of the housing 9 by the transport conveyor 8.
As will be understood from the disclosure of the present invention
set forth above, since the board to be dried is carried in the
horizontal direction and put on the uppermost extension arms of the
fork conveyors in a horizontal posture, the delivery of the board
onto the fork conveyors for drying treatment can be carried out
very easily without changing the horizontal posture of the board.
Likewise, the delivery of the dried board onto the discharge
conveyor from the fork conveyors can be carried out very easily,
since the discharge conveyor is provided below the fork conveyor
for discharging the dried board in the horizontal direction.
Further, since the board to be dried is fed from above the fork
conveyors and is received by the uppermost horizontal extension
arms of the fork conveyors, there is no difficulty in delivering a
small sized board to the fork conveyors, even if the board has an
irregular front end.
Furthermore, since the drying treatment is carried out by blowing
and circulating hot air against both faces of the board while being
horizontally supported and moved downwardly within the housing, the
conventional inconveniences such as imbalance of moisture content
in a finished state of the board and an arcuate deformation caused
by the difference in shrinkage can be eliminated and a
homogeneously dried board can be provided.
Furthermore, since the heater and fan are disposed in series at one
side portion of the housing, the hot air flows through the space
between the fork conveyors in the lengthwise direction of the
board. This flow pattern minimizes the curling or bending of the
dried board.
Although the present invention has been described with reference to
a preferred embodiment thereof, many modifications and alternations
can be made within the spirit of the present invention.
* * * * *